Tailpipe Acoustics and Backpressure Predictions of Exhaust Systems with Active and Passive Valves Technologies Utilizing GT-POWER

Transcription

1 1 Tailpipe Acoustics and Backpressure Predictions of Exhaust Systems with Active and Passive Valves Technologies Utilizing GT-POWER November 6 th 2017 Plymouth, Michigan, USA Gabriel Ostromecki

2 2 GT-POWER Valves backpressure and tailpipe noise simulations Agenda Valve usage in exhaust systems Active Electric Valves - usage examples Passive Spring Valves usage examples Spring valves GT-POWER simulation techniques Duct acoustics Why do valves reduce tailpipe noise acoustics? GT-POWER spring valve simulation acoustic correlation Summary Active Electric Valve Passive Spring In-Flow valve

3 GT-POWER Valves backpressure and tailpipe noise simulations Active Electric Valve usage example 3

4 GT-POWER Valves backpressure and tailpipe noise simulations Active Electric Valve usage example 4 Electric Valves for Tailpipe noise Acoustics Dual mode mufflers Controllable vehicle loudness and system backpressure Cylinder Deactivation Valve Tailpipe Sound Quality Valve

5 5 GT-POWER Valves backpressure and tailpipe noise simulations Passive Spring Valves usage examples Spring Valves Passive valves for increased attenuation with Backpressure hit Good attenuation on low engine flow rates (low RPM) Lower exhaust backpressure on high engine flow rates (high RPM) 1. Spring-Loaded Flapper Valve 2. In-Flow Spring-Loaded Valve Closed at low flow Open at High flow Valve Closed Path Valve Open Path

6 6 GT-POWER Valves backpressure and tailpipe noise simulations Passive Spring Valves usage examples 1. Flapper spring valve restriction mechanical model Dual flow muffler w/ restriction path when valve closed 1. Spring-Loaded Flapper Valve Valve Closed Path Valve Open Path

7 GT-POWER Valves backpressure and tailpipe noise simulations Passive Spring Valves usage examples Relative Backpressure (inhg) 7 1. Flapper spring valve restriction mechanical model GT-POWER template tuned for flow measured results 1.6 Valve Cold Room Temperature Mass Flow Rate (SCFM) Bench Data GT-Power

8 8 GT-POWER Valves backpressure and tailpipe noise simulations Spring Valves backpressure results example 2. In-Flow spring valve as variable restriction in exhaust system High restriction in low flow velocities Low restriction in high flow velocities Idle, POT WOT low RPM Lugging WOT high RPM 2. In-Flow Spring-Loaded Valve Closed at low flow Open at High flow

9 9 GT-POWER Valves backpressure and tailpipe noise simulations Spring In-flow Valves modeling correlation 2. In-Flow spring valve modeled as orifice connection with valve equivalent open area GT-POWER model tuned to match measured pressure drop Valve element

10 Transmission Loss (db) 10 GT-POWER Valves backpressure and tailpipe noise simulations Spring In-flow Valves modeling correlation Why in-flow spring, or electric valves works? Valve closed measured Acoustic Transmission Loss No effect of restriction measured without flow 50.8 Dia HP Valve 10 9 HP Valve Open HP Valve Closed Equivalent valve closed orifice Frequency (Hz) In flow spring valves or orifice in closed electric valve are invisible for transmission loss measurement w/o flow

11 11 GT-POWER Valves backpressure and tailpipe noise simulations Spring In-flow Valves modeling correlation Valve modeled as orifice connection with closed valve equivalent area GT-POWER Transmission Loss simulation as in measurements shows no significant effect of valve restriction Valve element

12 Insertion Loss (db) 12 GT-POWER Valves backpressure and tailpipe noise simulations Spring In-flow Valves modeling correlation Duct acoustics - sound pressure vs. particle velocity Insertion loss from engine results with flow shows great benefits of valves restriction sound pressure pattern in pipe 1st resonant frequency Dia HP Passive Valve in Outlet Pipe of Muffler Insertion Loss - I-4 Engine IL TL - Valve Closed 14 velocity antinode pressure node velocity node pressure antinode velocity antinode pressure node Insertion Loss Valve Open Valve Closed Engine measurement dominant order 6 Pressure difference reduce pipe resonance in high particle velocity patterns 4 2 Transmission Loss Equivalent valve closed orifice Frequency (Hz)

13 GT-POWER Valves backpressure and tailpipe noise simulations Spring In-flow Valves modeling correlation 13 Measurements vs. GT-POWER acoustic tailpipe noise correlation Valve Closed ~8dB improvement on pipe resonance 1st resonant frequency 120Hz sound pressure pattern in pipe 120Hz 120Hz Valve Closed ~8dB improvement on pipe resonance Valve open Minor effect on pipe resonance 120Hz Valve location

14 14 GT-POWER Valves Backpressure and Acoustic simulations Summary GT-POWER is appropriate tool to simulate both Backpressure and Acoustic Tailpipe noise of vehicle exhaust systems with electric and spring valves Both electric valves and spring valves can be easily modeled by orifice connection with tuned pressure loss and represent appropriate acoustic loss as well Mechanical representation of spring flap valves can bring very good correlation and allows to further tune Valve geometry Electric Valve In-Flow Valve Spring Flap Valve

15 15 Q & A Tailpipe Acoustics and Backpressure predictions of Exhaust Systems with Active and Passive Valves technologies utilizing GT-POWER Gabriel Ostromecki

16 16